Load "firefox_profile" from config file

[pablopaul]

For the future it would be way easier to have the possibility to load the selenium capability "firefox_profile" directly as file from the config rather then extending WebDriver.

@DavertMik initial thoughts on that:

Profiles.... I think we can add a config option to WebDriver module to load profile from a file. I think you can patch WebDriver module just as you did, but add profile_file into config and load data from file. Preferable to get profile stored in tests/_data dir, which is accessed via codecept_data_dir func

See #1188 for more details.

[pablopaul]

@DavertMik Please mark as "Enhancement"